PROPERTY, PLANT AND EQUIPMENT (Schedule of Property, Plant and Equipment) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 3,745,045	$ 3,699,416
Less - accumulated depreciation and amortization	2,217,101	2,174,118
Total property, plant and equipment, net	1,527,944	1,525,298
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	145,662	139,776
Asset retirement costs (non-landfill)
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	17,747	16,407
Landfill assets
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	193,009	191,687
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	514,711	509,804
Right-of-Use assets, finance leases	8,900	8,900
Camp equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	158,281	159,021
Vehicles
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	855,842	844,026
Right-of-Use assets, finance leases	56,400	47,200
Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,812,858	1,807,235
Right-of-Use assets, finance leases	9,400	9,300
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	6,992	7,082
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 39,943	$ 24,378